Artificial turf infill material

ABSTRACT

The invention provides for method for forming an artificial turf infill material. The method comprises selecting from a zeolite ore a microporous zeolite mineral using a selection criterion on specific surface area of the mineral, thereby providing the artificial turf infill material.

FIELD OF THE INVENTION

The invention relates to artificial turf, in particular to artificialturf with infill and also infill for artificial turf.

BACKGROUND AND RELATED ART

Artificial turf or artificial grass is a surface that is made up offibers which is used to replace grass. The structure of the artificialturf is designed such that the artificial turf has an appearance whichresembles grass. Typically artificial turf is used as a surface forsports such as soccer, American football, rugby, tennis, golf, forplaying fields, or exercise fields. Furthermore artificial turf isfrequently used for landscaping applications.

However, there is a need for a method and systems for controlling thetemperature at the surface of the artificial turfs. U.S. Pat. No.9,468,905 B2 discloses a composition for an outside surface ofartificial turfs in order to allow for an adsorption and/or desorptioneffect that optimizes the use of artificial turfs at high temperatures.

SUMMARY

The invention provides for an artificial turf, a method of forming anartificial turf infill and the use of the artificial turf infill in theindependent claims. Embodiments are given in the dependent claims.

In some embodiments, a method for forming an artificial turf infillmaterial is provided. The method comprises: providing a zeolite ore; andselecting from the zeolite ore a microporous zeolite mineral using aselection criterion on specific surface area of the mineral, therebyproviding the artificial turf infill material. For example, theselection may be performed by sorting by size the grains of the mineralsuch that the grains having a size higher than a predetermined maximumgrain size are rejected or filtered out and the grains having a sizebellow the maximum grain size form the microporous zeolite mineral.

The artificial turf may be used for a number of applications such assporting venues, landscape applications and green roofs on buildings.However, on playing fields, for example, the outside surfaces of theartificial turf are subject to the constraints of bad weather andtemperature variations that lead to problems in maintaining theseoutside surfaces in the conditions optimal for use. In order to solvesuch a problem, the present method provides a purposive selection of thezeolite mineral. This may enable to address specific purposes of the useof the artificial turf infill, wherein such purposes can be controlledvia the specific surface area. One example purpose is to enable the useof artificial turfs within the framework of bad weather and hightemperatures.

The determination of the specific surface area of the mineral isparticularly relevant for monitoring industrial processing of thezeolite minerals. The specific surface area constitutes an importantcriterion that enables the determination of the quality of a zeolitemineral since the nature of the specific surface area enables a decisivecharacteristic for the overall usage of zeolite. In particular the usageof the selected microporous zeolite mineral as an artificial turf infillmay have an impact on how realistically the artificial turf performs.

Artificial turf infill is a material that covers the bottom portion ofthe artificial turf fibers. The use of artificial turf infill of thepresent disclosure may further have a number of advantages. For example,artificial turf infill may help the artificial turf fibers stand upstraight. Artificial turf infill may also absorb impact from walking orrunning and provide an experience similar to being on real turf. Theartificial turf infill may also help to keep the artificial turf carpetflat and in place by weighting it down.

The selection of the microporous zeolite mineral may for examplecomprise crushing the zeolite ore for obtaining groups of zeolitematerials. The specific surface area of each group of the groups may bedetermined or measured. Based on the measured specific surface areagroups that fulfill the selection criterion may be selected to form themicroporous zeolite mineral. The specific surface area may for examplebe measured by adsorption using the Brunauer, Emmett, and Teller (BET)technique. This may have the advantage of measuring the surface of finestructures and deep texture on the particles.

The selection criterion refers to rules (e.g. classification rules) onthe basis of which it may be decided whether the specific surface areaof zeolite material is to be selected for forming the microporouszeolite mineral of the present method.

According to one embodiment, the selection criterion comprises: thespecific surface area is smaller than a predetermined maximum specificsurface area. Without putting an upper limit on the specific surfacearea, the infill material may comprise an inhomogeneous combination ofthe zeolite mineral. This embodiment may further be advantageous as itmay be simple to implement in particular where mineral productioninvolves repeated processes.

According to one embodiment, the method further comprises determiningthe maximum specific surface area of the mineral as the surface specificarea that enables the water in the mineral to release, under an ambienttemperature, at a predefined minimum rate. This embodiment may enable aprogressive release of the water by the microporous mineral and thus mayavoid rapid evaporation of the water after watering the surface. Thismay allow a lower temperature to be maintained at the level of the fieldsurface compared to the ambient temperature. For example, the controlledrelease of water causes progressive cooling under evaporation. Thus theamount of watering usually necessary to refresh a field surface may bereduced.

The present selected grain structure of the mineral enables theformation of bound water surrounding mineral surfaces and maintained byweak force of van der Waals force. This renders the release ordesorption of the water easier in particular under ambient temperature(e.g. the solar energy is enough to desorb the water). While the boundwater is releasing the water inside the grain may be transferred underambient temperature to the grain's surface which is then transformed towater vapor.

This may enable a progressive release of water over a predefined timeperiod and may enable the cooling of the surface of the artificial turf.

According to one embodiment, the selecting comprises: determining azeolite grain size corresponding to the maximum surface specific area;providing a grinding unit; reducing the zeolite ore into smaller zeolitefractions; setting parameters of the grinding unit in accordance withthe determined grain size; repeatedly grinding and screening the zeolitefractions in the grinding unit for selecting the microporous zeolitemineral. The grain size may refer to the diameter (e.g. maximumdiameter) of individual grains.

The repeatedly grinding and screening may comprise repeating thegrinding and the screening. In one example, the step of screening maycomprise multiple screening.

The multiple screenings may be of the same or different type screenings.For example, a screening of the multiple screening may comprise aninclined screening and another screening of the multiple screening maycomprise a horizontal screening. Performing multiple screening mayenable an optimal dedusting of the resulting microporous mineral.

According to one embodiment, the zeolite fractions have a maximum sizebetween 12 mm and 19 mm.

According to one embodiment, the reducing of the zeolite ore comprisescrushing the zeolite ore in a primary crusher, wherein the grinding unitcomprises a secondary crusher and a screening unit, wherein theparameters comprise at least one of: the number of decks of thescreening unit, the number of times the screening is to be repeated inthe screening step; the exciting force causing the vibration of thescreening unit; inclined and/or horizontal screening; reduction ratio ofthe primary and secondary crushers. A high number of parameters enablean optimal control of the grinding unit for providing an efficientproduction and selection of the microporous zeolite mineral.

According to one embodiment, the method further comprises drying thesmaller zeolite fractions in a dryer before the grinding. Dust generatedduring mineral production activities provides a pathway for theaccumulation of contaminants in the surrounding environment. Thisembodiment may have the advantage of reducing the amount of dust in theresulting microporous zeolite mineral.

According to one embodiment, the method further comprises shaping themicroporous zeolite mineral in a predefined shape, wherein the maximumspecific surface area is determined based on the solar reflectivity ofthe zeolite material having the predefined shape. The solar reflectivitydepends on the shape of the reflecting object. By controlling the shapeof the microporous zeolite mineral, the rate of the water release may bemore efficiently and uniformly controlled. This is because the range ofthe temperature under which the artificial turf is, may be controlled bythe solar reflectivity.

For example, the minimum rate may be determined for an ambienttemperature between min1 and max1 regardless of the shape of themicroporous zeolite mineral. If the artificial turf is to be implementedin a region having an ambient temperature between min2 and max2, theshape of the microporous zeolite mineral may be chosen such that thetemperature at the surface of the turf is between min1 and max1.

According to one embodiment, the artificial turf infill is themicroporous zeolite mineral. The microporous zeolite mineral is the onlyinfill material. This may provide safe and environmental friendlyartificial turfs.

According to one embodiment, the porosity of the zeolite ore is between15% to 20%, wherein the maximum specific surface area is between 20 m²/gand 35 m²/g. In a preferred embodiment the maximum specific surface areais between 15 m²/g and 25 m²/g. In a very preferred embodiment themaximum specific surface area is between 19 m²/g and 21 m²/g. Forexample, the selected specific surface area may be 20 m²/g themicroporous zeolite mineral having a porosity of 20%.

According to one embodiment, the ambient temperature is between 40° C.and 60° C. or below 100° C. “Ambient temperature” refers to atemperature of the air that surrounds the artificial turf undercircumstances without any special heating and cooling. For example, theminimum rate may be determined using the usage time of the artificialturf. For a playing field, the minimum rate may be determined based onthe game duration time e.g. such that the water progressively releasesduring the entire game.

According to one embodiment, the method further comprises: determiningthe maximum specific surface area such that in the presence of humidity,the mineral absorbs the humidity.

The humidity absorption refers to the moisture buffering capacity of themicroporous zeolite mineral. This embodiment may prevent, for example,in the cold season the appearance of frost which renders the surfaceshard and slippery and thus dangerous to use.

According to one embodiment, the microporous zeolite mineral has a grainsize between 0.5 mm and 1.2 mm or between 0.9 mm and 1.2 mm. Theselected size may have the further advantage of protecting the users ofthe artificial turf by reducing the risk of skin injury when the usersare in contact the infill material. This may also prevent a slipperysurface of the artificial turf.

According to one embodiment, 0.6% of the mineral is not retainable on a100 mesh screen. This may provide another means (e.g. in combinationwith the drying) for further controlling the amount of dust in theresulting microporous zeolite mineral.

According to one embodiment, the microporous zeolite mineral has ahardness between 3 and 4 on the Mohs scale. This may provide a soft andresilient playing surface. This may reduce the risk of injuries (e.g.skin abrasion). Another advantage may be that the present infillmaterial by reducing the wear effect of synthetic turf fibers caused bythe friction between the zeolite mineral and the fibers.

For example, the amount of arsenic in the microporous zeolite mineral isbelow 4 mg per kg of the mineral. This may provide a healthy material.

In some embodiments, a method for controlling the temperature on anartificial turf is provided. The method comprises providing amicroporous zeolite mineral having a selected specific surface area ofthe mineral; and using the microporous zeolite mineral as an infillmaterial of the artificial turf.

According to one embodiment, the microporous zeolite mineral has a colorwith a predefined brightness, wherein the specific surface area of themineral being selected based on the predefined brightness. The color mayfor example be white and the brightness may be equal to 85. Thisprovides an additional parameter for an optimal control of thetemperature at the surface of the artificial turf. The determination ofthe specific surface area may be modulated or combined with thebrightness by balancing between the two parameters values in order toobtain the minimum rate.

In some embodiments, an artificial turf is provided. The artificial turfcomprises an artificial turf carpet with a pile and artificial turfinfill, wherein the artificial turf carpet comprises a backing; whereinthe artificial turf carpet further comprises artificial grass fibers,wherein the artificial grass fibers are tufted into the backing, whereinthe artificial grass fibers form the pile, wherein the artificial grassfibers are secured to the backing, wherein the artificial turf infillcomprises a microporous zeolite mineral having a selected specificsurface area of the mineral.

According to one embodiment, the artificial turf further comprises asprinkler system. The use of a sprinkler system with the artificial turfmay be beneficial because it may be used to automatically wet theartificial turf infill. For example this may be a convenient means ofwatering the artificial turf during a time period that is defined basedon the minimum release rate of the water from the microporous zeolitemineral. For example, the selected microporous mineral may have aspecific surface area which enables the water to progressively releaseduring the half time period of a football game. In this case, thesprinkler system may be configured to water the artificial turf duringthe half-time break of the game.

In some embodiments, an artificial turf infill material is provided. Theartificial turf infill material comprises a microporous zeolite mineralhaving a selected gain size smaller than 1.5 mm and a porosity between15% and 20%.

According to one embodiment, the microporous zeolite mineral has a grainsize distribution as follows: 70% to 90% of the grains have a size inthe range [0.4 mm, 1.5 mm] and 10% to 30% of the grains have a sizesmaller than 0.4 mm. In another example, the microporous zeolite mineralhas a grain size distribution as follows: 70% to 90% (e.g. 88%) of thegrains of the microporous zeolite mineral have a size in the range [0.42mm, 1.41 mm] (14-40 mesh) and 10% to 30% (e.g. 12%) of the grains ofmicroporous zeolite mineral have a size smaller than 0.42 mm. Theselected sizes may enable to obtain the selected specific surface area.

According to one embodiment, 0.6% of the mineral at most is notretainable on a 100 mesh screen.

According to one embodiment, the microporous zeolite mineral has ahardness between 3 and 4 on the Mohs scale.

The infill material of any of the preceding claims 22-25, wherein themoisture level in the mineral is smaller than 6%

It is understood that one or more of the aforementioned embodiments ofthe invention may be combined as long as the combined embodiments arenot mutually exclusive.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following embodiments of the invention are explained in greaterdetail, by way of example only, making reference to the drawings inwhich:

FIG. 1 is a flowchart of a method for forming an artificial turf infillmaterial

FIG. 2 is a flowchart of an example method for selecting a microporouszeolite mineral from the zeolite ore;

FIG. 3 is a flowchart of another example method for selecting amicroporous zeolite mineral from the zeolite ore;

FIG. 4A illustrates an example of an artificial turf;

FIG. 4B illustrates a further example of an artificial turf;

FIG. 4C illustrates a further example of an artificial turf; and

FIG. 5 illustrates an example of an artificial turf which incorporates asprinkler system.

DETAILED DESCRIPTION

Like numbered elements in these figures are either equivalent elementsor perform the same function. Elements which have been discussedpreviously will not necessarily be discussed in later figures if thefunction is equivalent.

FIG. 1 is a flowchart of a method for forming an artificial turf infillmaterial. The infill material may be included in artificial turfs asdescribed with reference to FIGS. 4A-5.

In step 101, a zeolite ore may be provided. The zeolite ore is anaturally occurring solid material. The zeolite ore has a porositybetween of 15% and 20%. The term “porosity” refers to the volumefraction of void space in a porous article. The zeolite phase of thezeolite ore may comprise one or more of the group consisting ofclinoptilolite, mordenite, or other naturally occurring zeoliteminerals.

The zeolite ore may be provided for example as follows. A zeolitedeposit is stripped of overburden and stockpiled for use in subsequentmine reclamation. The resulting exposed ore body is drilled to depthsbetween 12 and 14 feet. The drill holes are loaded with an explosivecharge that degenerates upon use, leaving no residue in the zeolite ore.From the mine pit, the zeolite ore is hauled by dump truck to the crudeore stockpile at a processing mill.

In step 103, a microporous zeolite mineral may be selected from thezeolite ore. The selection may be performed using a selection criterioninvolving the specific surface area of the mineral. The selectioncriterion may refer to one or more rules on the specific surface area.

For example, the selection of step 103 comprises a selective recoveringor obtaining of the microporous zeolite mineral having a predefinedspecific surface area from the zeolite ore. The specific surface areaconstitutes an important criterion that is involved in the determinationof the quality of a zeolite mineral since the nature of the specificsurface area enables a decisive characteristic for the overall usage ofzeolite in numerous technical components and products. For example, aspecific surface area which is too high may render the release of waterunder ambient temperature very slow or inexistent.

In one example, the selection criterion requires that the specificsurface area is smaller than a predetermined maximum specific surfacearea. The maximum specific surface area of the mineral may for examplebe determined as the surface specific area that enables the water in themineral to release, under an ambient temperature, at a predefinedminimum rate. For example, for a specific surface area equal or higherthan 40 m²/g the water may only release under temperatures which arehigher than the maximum ambient temperatures. Those high temperaturesrequire the use of an oven. The present method may be advantageous asthe maximum surface specific area that is selected enables the water torelease under ambient temperatures e.g. between 40 and 60 C. Theselected specific surface area may for example be 20 m²/g for a porosityof 15% to 20%.

In another example, the maximum specific surface area is chosen suchthat at most 0.6% of the mineral is not retainable on a 100 mesh screene.g. 94% of the mineral has a grain size higher than 0.15 mm. This mayhave the advantage of reducing the amount of dust in addition toenabling a progressive release of the water for an optimal cooling ofthe artificial turf. Reducing the amount of dust may be beneficial forimproving the safety of the product as regards the protection of therespiratory system of users of the artificial turf.

The selected microporous zeolite mineral may be used as the artificialinfill material. In on example, the artificial infill material mayconsist of the selected microporous zeolite mineral. In another example,the artificial infill material may comprise the selected microporouszeolite mineral in addition to other infill materials.

FIG. 2 is a flowchart of an example method for selecting a microporouszeolite mineral from the zeolite ore (e.g. the zeolite ore provided instep 101) using a grinding unit. The grinding unit is configured forperforming the grinding and screening of zeolite materials. The grindingunit may have parameters for controlling its function. The parametersmay for example comprise the reduction ratio of the grinding unit, thenumber of times the screening is to be repeated in the screening step;the exciting force causing the vibration of the screening unit; inclinedand/or horizontal screening.

In step 201, a zeolite grain size that corresponds to the maximumsurface specific area may be determined. The grain size of themicroporous zeolite mineral is determined such that the resultingspecific surface area of the mineral is smaller than the maximumspecific surface area.

Naturally, the specific surface area of the microporous zeolite mineralvaries with its structure. For example, the finer the mineral is, thelarger the specific surface area is (i.e. the smaller the grain size is,the larger the specific surface area is).

For example, the specific surface area of the microporous zeolitemineral may not exceed a minimum specific surface area. The minimumspecific surface area may be the smallest possible specific surfacearea. In this case, the determined grain size may be the lower limit ofa range of sizes, wherein the upper limit of the range may be determinedusing the minimum specific surface area. The microporous zeolite mineralmay for example have a grain size between 0.5 mm and 1.2 mm or between0.9 mm and 1.2 mm, for a maximum surface specific surface area of 21m²/g (e.g. the selected specific surface area may be 20 m²/g).

In step 203, the zeolite ore may be reduced into smaller zeolitefractions. FIG. 3 shows an example method for reducing the zeolite oreinto smaller fractions. The zeolite fractions may for example have amaximum size of ⅝ inch. In order to obtain that maximum size for thefractions, the reducing of the zeolite ore may comprise in addition tocrushing the zeolite ore, a sieving or screening step, wherein in thescreening step the crushed zeolite ores are screened with series ofsieves. For example, the series of sieves may comprise sieves havingsieve sizes ranging from about a minus 14 mesh (1.41 mm) to about a plus40 mesh (0.42 mm).

In step 205, parameters of the grinding unit may be set in accordancewith the determined grain size of step 201. For example, the reductionratio of the grinding unit may be set such that the grinding unit mayprovide or output from the zeolite fractions grains having as a maximumsize the determined grain size.

In one example, before performing the grinding step 207, the zeolitefractions resulting from step 203 may be dried in a dryer. This may havethe advantage of reducing the amount of dust in the resultingmicroporous zeolite mineral.

In step 207, the zeolite fractions may be grind in the grinding unit.The term “grinding” encompasses processes like cutting, chopping,crushing, milling, pulverizing, and the like.

After grinding the zeolite fractions, the resulting zeolite material maybe screened in step 208, resulting in groups of zeolite grains, whereineach group has a respective minimum grain size. The screening may forexample be performed using series of sieves having sieve sizes rangingfrom about a minus 14 mesh (1.41 mm) to about a plus 40 mesh (0.42 mm).The screening may be a vibratory-type screening.

In one example, up to six or more different fractions can be separatedin one screening process. This may for example be done using multiplesieve decks positioned on top of each other in a classification rangesuch as a range of 0.1 mm to 1.5 mm.

The maximum grain size of each group of the groups may be compared withthe determined grain size of step 201. In case (inquiry 209) the minimumgrain size of a group of the groups is higher than the determined grainsize, step 208 or steps 207-208 may be repeated. Otherwise, the groupmay be selected and stored in step 211 as part of the selectedmicroporous zeolite mineral.

For example, the method may end if the selected microporous zeolitemineral reaches a predefined amount or if the input ore is completed.

FIG. 3 illustrates the process of selecting a microporous zeolitemineral from a zeolite ore (e.g. zeolite ore of step 101) in accordancewith another example of the present disclosure. FIG. 3 shows a crushingunit 301 and a grinding unit 302, wherein the zeolite ore is firstprocessed at the crushing unit 301 and the resulting material is inputto the grinding unit 302 for further processing.

Before processing the zeolite ore in the crushing unit 301, the zeoliteore may for example be obtained as follows. A zeolite deposit isstripped of overburden and stockpiled for use in subsequent minereclamation. The resulting exposed ore body is drilled to depths between12 and 14 feet. The drill holes are loaded with an explosive charge thatdegenerates upon use, leaving no residue in the zeolite ore. From themine pit, the zeolite ore is hauled by dump truck to the crude orestockpile at a processing mill.

The zeolite ore is fed in step 31 through a grizzly 303 with 16″×16″opening, the output ore of the grizzly 303 travels in step 32 via afirst conveyer into a jaw crusher 305 where the output ore of thegrizzly 303 is reduced to a 4 inch size resulting in 4 inch ore. The 4inch ore travels in step 33 via a second conveyor to a double deckNordberg screen 307 with a ⅝ inch screen on the top deck. The resultingoutput of the double deck Nordberg screen 307 is a minus ⅝ inch materialand plus ⅝ inch material.

The minus ⅝ inch material travels in step 34 to a third conveyor towardthe grinding unit 302 via a dryer 311. The plus ⅝ inch material travelsback in step 35 via a fourth conveyor to a cone crusher 309 whichreduces the plus ⅝ inch material to at least ½ inch material. The ½ inchmaterial then returns in step 37 to the Nordberg screen 307 via thesecond conveyor.

From the third conveyor, the zeolite material output of the Nordbergscreen 307 travels in step 34 to a propane fueled rotary kiln dryer 311where it is heated at 250° C., reducing moisture to 5%, and fed in step38 to the grinding unit 302.

The zeolite material is conveyed in step 38 from the dryer 311 via afifth conveyor to an impact crusher 313 and five-decked Midwesternscreens 315. From the screens 315 the zeolite is sized and conveyed instep 39 to a sixth conveyor for packaging e.g. in super sacks 320 readyto ship or the zeolite is returned in step 40 via a seventh conveyor tothe impact crusher 313 and which is returned to the Midwestern Screens315. At the Midwestern screens 315, the products are sized according tocustomer specifications and either sent to finished product handling. Inthe finished product handling process: a. the material is either sent tobulk storage silos for direct truck loading or b. The material is sentto packaging silos where it is packaged in customer specified bags andpalletized, wrapped, and stored in warehouse for truck pick up.

The following table gives example properties of the selected microporouszeolite mineral of the present method.

Parameter Values Granulometry 14 × 40 mesh (0.42-1.39 mm) Particle sizedistribution 14 mesh (1.39 mm)  0.9% 20 mesh (0.84 mm) 39.0% 30 mesh(0.59 mm) 27.0% 40 mesh (0.42 mm) 21.0% 100 mesh (0.15 mm) 10.0% <100mesh  0.6% color/Brightness White/85 Hardness 3 Porosity 15-20%  Arsenictotal <4 mg/kg sec Level of humidity  ≤6%

The values of the parameters, particle size or grain size, color,hardness, arsenic total and level of humidity, listed in the table arecentral values. However, each parameter of these parameters may have avalue in the range defined by the central value, ±10%, ±5% or ±3% of thecentral value. These values may for example enable to obtain a specificsurface area of 20 m²/g.

FIG. 4A shows an example of an artificial turf 400A. The artificial turf400A comprises an artificial turf carpet 402. The artificial turf carpetcomprises a backing 404 and also artificial grass fibers 406. Theartificial grass fibers 406 are tufted into the backing 404 and aresecured 408 to the backing 404. The artificial turf fibers 406 form apile 403. The artificial turf carpet 402 is resting on a ground 410 orsurface. Between and distributed between the artificial grass fibers 406and within the pile 403 is an artificial turf infill 412. The infillartificial turf infill 412 is shown as having a cylindrical shape;however it may have other shapes. For example, the shape of themicroporous zeolite mineral may be a spherical shape. In this examplethe artificial turf infill 412 is made from at least the selectedmicroporous zeolite mineral 414. In on example, the artificial infillmaterial may consist of the selected microporous zeolite mineral. Inanother example, the artificial infill material may comprise theselected microporous zeolite mineral in addition to other infillmaterials.

FIG. 4B shows a further example of an artificial turf 400B. Theartificial turf 400B is similar to the artificial turf 400A shown inFIG. 4A except there is additionally a sand layer 420 between theartificial turf infill 412 and the backing 404. The use of the sandlayer 420 may be advantageous because it may help to hold the artificialturf carpet 402 in place. It may also have the technical benefit thatthe sand layer 430 works in conjunction with the artificial turf infill412 to regulate the amount of water on the surface of the artificialturf 400B. For example if it rains or if water is sprayed onto thesurface of the artificial turf 400B the composite infill components 414may rapidly absorb and saturate with water. The sand layer 420 may thenaid in draining away excess water and preventing it from standing on thesurface of the artificial turf 400B.

FIG. 4C shows a further example of an artificial turf 400C. Theartificial turf 400C is similar to the artificial turf 400B shown inFIG. 4B with the addition of several additional layers. Directlyunderneath the backing 404 is an elastic layer 432. The elastic layer432 may for example be a mat or other material such as sand andelastomeric granulate or a mixture thereof that readily absorbs shock.The elastic layer 432 is optional. The backing 404 and/or the elasticlayer 432 may have holes or may be porous so that water that is standingon the artificial turf 400C can be drained away. The elastic layer 432is directly sitting on a drainage system 430. The drainage system 430may comprise granulate material, drainage tiles, drainage pipes or othersystem for rapidly draining water off the surface of the artificial turf400C. The artificial turf depicted in FIG. 4C may have superiorqualities when water is used to cool or improve sliding properties.Water that initially goes on the surface may readily be absorbed by thecomposite infill components 414 that make up the artificial turf infill412. When they have filled with water excess water may then go into andpossibly be stored in the sand layer 420. When the sand layer 420 issaturated it may drain through the backing 404 and/or the elastic layer432 into the drainage system 430.

FIG. 5 shows a further example of the artificial turf e.g. 400A. In thisexample an automatic sprinkler system 500 has been integrated into theartificial turf 400A. The sprinkler 500 is depicted as spraying water502 on an upper surface of the artificial turf 400A. The use of thesprinkler may be beneficial in combination with the artificial turf asit may provide an integrated watering system for an optimal watering ofthe artificial turf.

LIST OF REFERENCE NUMERALS

-   -   31-40 method steps    -   101-103 method steps    -   201-211 method steps    -   301 crushing unit    -   302 grinding unit    -   303 grizzly    -   305 jaw crusher    -   307 Nordberg screen    -   309 cone crusher    -   311 dryer    -   313 impact crusher    -   315 Midwestern screens    -   320 sack    -   400A artificial turf    -   402 artificial turf carpet    -   403 pile    -   404 backing    -   406 artificial grass fibers    -   408 secured to backing    -   410 ground    -   412 artificial turf infill    -   414 composite infill component    -   400B artificial turf    -   420 sand layer    -   400C artificial turf infill    -   432 elastic layer    -   430 drainage system    -   500 sprinkler system    -   502 spraying water.

1. A method for forming an artificial turf infill material, the methodcomprising: providing a zeolite ore; selecting from the zeolite ore amicroporous zeolite mineral using a selection criterion on specificsurface area of the mineral, thereby providing the artificial turfinfill material.
 2. The method of claim 1, the selection criterioncomprising: the specific surface area is smaller than a predeterminedmaximum specific surface area.
 3. The method of claim 2, furthercomprising determining the maximum specific surface area of the mineralas the surface specific area that enables the water in the mineral torelease, under an ambient temperature, at a predefined minimum rate. 4.The method of claim 3, the selecting comprising: determining a zeolitegrain size corresponding to the maximum surface specific area; providinga grinding unit; reducing the zeolite ore into smaller zeolitefractions; setting parameters of the grinding unit in accordance withthe determined grain size; repeatedly grinding and screening the zeolitefractions in the grinding unit for selecting the microporous zeolitemineral.
 5. The method of claim 4, wherein the zeolite fractions have amaximum size of ⅝ inch.
 6. The method of claim 4, the reducing of thezeolite ore comprising crushing the zeolite ore in a primary crusher,wherein the grinding unit comprises a secondary crusher and a screeningunit, wherein the parameters comprise at least one of: the number ofdecks of the screening unit, the number of times the screening is to berepeated in the screening step; the exciting force causing the vibrationof the screening unit; inclined and/or horizontal screening; reductionratio of the primary and secondary crushers.
 7. The method of claim 4,further comprising drying the smaller zeolite fractions in a dryerbefore the grinding.
 8. The method of claim 1, further comprisingshaping the microporous zeolite mineral in a predefined shape, whereinthe maximum specific surface area is determined based on the solarreflectivity of the mineral having the predefined shape.
 9. The methodof claim 1, wherein the artificial turf infill material is themicroporous zeolite mineral.
 10. The method of claim 1, wherein theporosity of the zeolite ore is between 15% to 20%, wherein the maximumspecific surface area is between 20 m²/g and 35 m²/g.
 11. The method ofclaim 1, wherein the ambient temperature is between 40° C. and 60° C. orbelow 100° C.
 12. The method of claim 1, the method further comprising:determining the maximum specific surface area such that in the presenceof humidity, the mineral absorbs the humidity.
 13. The method of claim1, wherein the microporous zeolite mineral has a grain size between 0.5mm and 1.2 mm or between 0.9 mm and 1.2 mm.
 14. The method of claim 1,wherein 0.6% of the mineral at most is not retainable on a 100 meshscreen.
 15. The method of claim 1, the microporous zeolite mineralhaving a hardness between 3 and 4 on the Mohs scale.
 16. The method ofclaim 1, wherein the microporous zeolite mineral has a grain sizedistribution as follows: 70% to 90% of the grains have a size in therange [0.4 mm, 1.5 mm] and 10% to 30% of the grains have a size smallerthan 0.4 mm, wherein the moisture level in the mineral is smaller than6%.
 17. A method for controlling the temperature on an artificial turf:providing a microporous zeolite mineral having a selected specificsurface area; using the microporous zeolite mineral as an infillmaterial of the artificial turf.
 18. The method of claim 17, the mineralhaving a color with a predefined brightness, wherein the specificsurface area being selected based on the predefined brightness.
 19. Anartificial turf comprising an artificial turf carpet with a pile andartificial turf infill, wherein the artificial turf carpet comprises abacking; wherein the artificial turf carpet further comprises artificialgrass fibers, wherein the artificial grass fibers are tufted into thebacking, wherein the artificial grass fibers form the pile, wherein theartificial grass fibers are secured to the backing, wherein theartificial turf infill comprises a microporous zeolite mineral having aselected specific surface area.
 20. The artificial turf of claim 19,wherein the artificial turf further comprises a sprinkler system.
 21. Anartificial turf infill material comprising a microporous zeolite mineralhaving a selected gain size smaller than 1.5 mm and a porosity between15% and 20%.
 22. The infill material of claim 21, wherein themicroporous zeolite mineral has a grain size distribution as follows:70% to 90% of the grains have a size in the range [0.4 mm, 1.5 mm] and10% to 30% of the grains have a size smaller than 0.4 mm.
 23. The infillmaterial of claim 21, wherein 0.6% of the mineral at most is notretainable on a 100 mesh screen.
 24. The infill material of any of thepreceding claim 21, the microporous zeolite mineral having a hardnessbetween 3 and 4 on the Mohs scale.
 25. The infill material of any of thepreceding claim 21, wherein the moisture level in the mineral is smallerthan 6%.